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BOZېࢭ
ઈରʹܕ͚ΛఘΊͳ͍ͨΊͷ
ศརͳϢʔςΟ
ϦςΟؔ
/PW
TUBOEGN5&$)45"/%5ZQF4DSJQU
!PLVOPLFOUBSP
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୭
w Ԟݡଠ!PLVOPLFOUBSP
w ΫϨεΣΞגࣜձࣾ
w 5ZQF4DSJQUྺ
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ܕɺ
ͪΌΜͱ͚ͯ·͔͢
const res = await fetch('/api/users', {method: 'GET'});
const users = await res.json();
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͜ΕͰຬͯ͠ͳ͍
ʁ
const res = await fetch('/api/users', {method: 'GET'});
const users = await res.json() as User[];
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anyܕʹas TΛࢦఆ͢Δͷةݥ
wʮanyܕةݥʯ
ʜͱ͍͏ཧղ͍ͯͯ͠ɺ
as TͳΒฏؾͰͬͯ͠·
͏ݱগͳ͘ͳ͍
w Ͱ
ʮany as Tةݥʯ
w anyܕͷʹas T
ʢas User[]ͳͲʣ
Λ͚ͯίϯύΠϧΤϥʔʹͳΒͳ͍
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ͳʹ͕ةݥͳͷ͔
w ͍͘
ΒͰӕ͕͚ͭΔ
w ίϯύΠϧ௨͍ͬͯͯɺ
࣮ࡍʹͦ͜ʹྲྀΕͯ͘
ΔͷߏҟͳΔঢ়گ
w as T
ʮίϯύΠ
ϥΛ͍͍ٗͯΔ͚ͩʯ
Ͱ͋Δ
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͜ͷίʔ
υΤϥʔʹͳΒͳ͍
const res1 = await fetch('/api/users', {method: 'GET'});
const users = await res1.json() as User[];
const res2 = await fetch('/api/items', {method: 'GET'});
const items = await res2.json() as User[];
as Item[] Ͱʁʁ
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asΛΘͣ҆શʹܕ͚Λ͢Δ
w anyېࢭasېࢭ
w 5ZQFQSFEJDBUFTΛ͏
IUUQTXXXUZQFTDSJQUMBOHPSHEPDTIBOECPPLOBSSPXJOHIUNMVTJOHUZQFQSFEJDBUFT
w function isSomething(v: unknown): v is Something { ...
Έ͍ͨͳͭ
w JG݅ࣜʹͯisSomething(v)ΛͬͨΒɺ
ͦͷJGϒϩοΫͰv͕Somethingܕͱͯ͠ѻ͑Δ
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type User = {
id: number;
name: string;
};
function hasId(v: unknown): v is { id: unknown } {
if (typeof v !== "object" || v === null) {
return false;
}
return "id" in v;
}
function hasName(v: unknown): v is { name: unknown } {
if (typeof v !== "object" || v === null) {
return false;
}
return "name" in v;
}
function isUser(v: unknown): v is User {
if (!hasId(v) || !hasName(v)) {
return false;
}
if (typeof v.id !== "number") {
return false;
}
if (typeof v.name !== "string") {
return false;
}
return true;
}
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ׂͱखؒ
w asΛઈ໓ͤ͞Α
͏
ͱͨ͠Βɺ
5ZQFQSFEJDBUFT͕ؔͨ͘
͞Μඞཁ
w JGϒϩοΫͷதͰ͔͠ਪ͞Εͳ͍ͷͰɺ
ίʔ
υ͕ෳࡶʹͳΓ͕ͪ
w JGϒϩοΫ͕ඞਢͳͷ໘
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JGจΛΘͳ͍
w "TTFSUJPOGVODUJPOTΛ͏
IUUQTXXXUZQFTDSJQUMBOHPSHEPDTIBOECPPLSFMFBTFOPUFTUZQFTDSJQUIUNMBTTFSUJPOGVODUJPOT
w function assertSomething(
v: unknown): asserts v is Something { ...
Έ͍ͨͳͭ
w assertSomething(v)ΛͬͨΒɺ
ͦͷ͕ؔྫ֎Λ͛ͳ͍ݶΓ
ಉҰείʔϓͷҎ߱ͷεςʔ
τϝϯ
τͰv͕Somethingܕͱͯ͠ѻ͑Δ
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type User = {
id: number;
name: string;
};
function assertId(v: unknown): asserts v is { id: unknown } {
if (typeof v !== "object" || v === null) {
throw new Error("Value should be non-null object");
}
if (!("id" in v)) {
throw new Error('Value should have the property "id"');
}
// noop
}
function assertName(v: unknown): asserts v is { name: unknown } {
if (typeof v !== "object" || v === null) {
throw new Error("Value should be non-null object");
}
if (!("name" in v)) {
throw new Error('Value should have the property "name"');
}
// noop
}
function assertUser(v: unknown): asserts v is User {
assertId(v);
assertName(v);
if (typeof v.id !== "number") {
throw new Error('"id" should be a number');
}
if (typeof v.name !== "string") {
throw new Error('"name" should be a string');
}
// noop
}
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ͬͺΓखؒ
w asΛઈ໓ͤ͞ΔͨΊʹ͜͜·Ͱ͢Δ
ʁ
w ҰͭͷΦϒδΣΫ
τʹ͍ͭͯݕূ͢Δ͚ͩͰؔଟ͗͢͡Όͳ͍
ʁ
w ͏asΛ͍͍ͬͯΜ͡Όʜ
ʁ
w ઈରʹఘΊͳ͍
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ศརؔΛ࡞ͬͯΈͨ
w ϓϩύςΟ͕ੜ͍͑ͯΔ͜ͱΛϥϯλΠϜͰݕূͭͭ͠
w ܕͪΌΜͱ͍ͯ͘Εͯ
w ͔͠ܕఆٛΛमਖ਼ͨ͠ΒϥϯλΠϜͰ
ݕূ͞ΕΔϓϩύςΟ
ैͯ͠΄͍͠
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type UnionToIntersection = (U extends any ? (k: U) => void : never) extends (
k: infer I
) => void
? I
: never;
type LastOf = UnionToIntersection<
T extends any ? () => T : never
> extends () => infer R
? R
: never;
type Push = [...T, V];
type UnionToTuple<
T,
L = LastOf,
N = [T] extends [never] ? true : false
> = true extends N ? [] : Push>, L>;
type Tuple = [TItem, ...TItem[]] & {
length: TLength;
};
/**
* Tuple [string, string, string] Λฦ͢
* ͦΕΛԠ༻ͯ͠ 'a' | 'b' Λ ['a' | 'b', 'a' | 'b'] ʹ͢Δ
*
* 'a' | 'b'
* => ['a' | 'b', 'a' | 'b']
* 'a' | 'b' | 'c'
* => ['a' | 'b' | 'c', 'a' | 'b' | 'c', 'a' | 'b' | 'c']
*/
type UnionToUnionTuple = Tuple["length"]>;
type TypeEq = (() => T extends A ? 1 : 2) extends () => T extends B
? 1
: 2
? true
: false;
type RemoveNeverProperties = Pick<
T,
{
[P in keyof T]: [T[P]] extends [never] ? never : P;
}[keyof T]
>;
type AnyAs0 = {
[P in keyof T]: TypeEq extends true ? 0 : T[P];
};
type UnknownAs0 = {
[P in keyof T]: TypeEq extends true ? 0 : T[P];
};
type OptionalAsUndefined = {
[P in keyof T]: T[P] extends NonNullable ? T[P] : undefined;
};
type UndefinedAsNever = {
[P in keyof T]-?: T[P] extends undefined ? never : T[P];
};
/**
* { a?: string; b: number; c?: any; d: any } Λ
* { b: number; d: any } ͚ͩʹ͢Δɻ
*
* AnyAs0 ͕ͳ͍ͱ ?: any ͷରԠ͕࿙ΕΔͷͰҙɻ
*/
type RemoveOptionalProperties = {
[P in keyof RemoveNeverProperties<
UndefinedAsNever>>>
>]: T[P];
};
function isObject(v: unknown): v is Record {
if (typeof v !== "object") {
return false;
}
return v !== null;
}
function assertObject(
v: unknown,
target = ""
): asserts v is Record {
if (!isObject(v)) {
throw new Error(`${target} should be object`.trim());
}
}
function isMatchedType(
v: unknown,
props: UnionToUnionTuple>,
errorPropsRef: string[],
target = ""
): v is T {
assertObject(v, target);
if (new Set(props).size !== props.length) {
throw new Error("Invalid props");
}
return props
.map((prop) => {
if (typeof prop !== "string") {
throw new Error("Invalid prop");
}
const within = prop in v;
if (!within) {
errorPropsRef.push(prop); // mutate
}
return within;
})
.every((flag) => flag);
}
export function assertMatchedType(
v: unknown,
props: UnionToUnionTuple>,
target = ""
): asserts v is T {
const errorPropsRef: string[] = []; // ࢠʹΛ֨ೲͤ͞ΔͨΊͷۭྻࢀর
if (!isMatchedType(v, props, errorPropsRef, target)) {
// ͜͜ʹ֘͢Δͱ͖ errorPropsRef ྻͷதʹΤϥʔՕॴ͕٧·͍ͬͯΔɻ
throw new Error(
`${target} should be aligned type. ${
0 < errorPropsRef.length ? `[${errorPropsRef.join(", ")}]` : ""
}`.trim()
);
}
}
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.map((prop) => {
if (typeof prop !== "string") {
throw new Error("Invalid prop");
}
const within = prop in v;
if (!within) {
errorPropsRef.push(prop); // mutate
}
return within;
})
.every((flag) => flag);
}
export function assertMatchedType(
v: unknown,
props: UnionToUnionTuple>,
target = ""
): asserts v is T {
const errorPropsRef: string[] = []; // ࢠʹΛ֨ೲͤ͞ΔͨΊͷۭྻࢀর
if (!isMatchedType(v, props, errorPropsRef, target)) {
// ͜͜ʹ֘͢Δͱ͖ errorPropsRef ྻͷதʹΤϥʔՕॴ͕٧·͍ͬͯΔɻ
throw new Error(
`${target} should be aligned type. ${
0 < errorPropsRef.length ? `[${errorPropsRef.join(", ")}]` : ""
}`.trim()
);
}
}
ͳʹΛ࡞͔ͬͨ
w assertMatchedType()ؔΛ࣮ͨ͠
w ୈҾʹݕূ͍ͨ͠ΦϒδΣΫ
τ
w ୈҾʹݕূ͍ͨ͠ϓϩύςΟ໊ͷྻ
w ܕύϥϝʔλʹཧͷܕఆٛΛॻ͘
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.map((prop) => {
if (typeof prop !== "string") {
throw new Error("Invalid prop");
}
const within = prop in v;
if (!within) {
errorPropsRef.push(prop); // mutate
}
return within;
})
.every((flag) => flag);
}
export function assertMatchedType(
v: unknown,
props: UnionToUnionTuple>,
target = ""
): asserts v is T {
const errorPropsRef: string[] = []; // ࢠʹΛ֨ೲͤ͞ΔͨΊͷۭྻࢀর
if (!isMatchedType(v, props, errorPropsRef, target)) {
// ͜͜ʹ֘͢Δͱ͖ errorPropsRef ྻͷதʹΤϥʔՕॴ͕٧·͍ͬͯΔɻ
throw new Error(
`${target} should be aligned type. ${
0 < errorPropsRef.length ? `[${errorPropsRef.join(", ")}]` : ""
}`.trim()
);
}
}
ͳʹΛ࡞͔ͬͨ
w assertMatchedType()ؔΛ࣮ͨ͠
w ୈҾʹݕূ͍ͨ͠ΦϒδΣΫ
τ
w ୈҾʹݕূ͍ͨ͠ϓϩύςΟ໊ͷྻ
w ܕύϥϝʔλʹཧͷܕఆٛΛॻ͘
type User = {
id: number;
name: string;
};
const obj: unknown = { id: 1, name: "foo" };
assertMatchedType(obj, ["id", "name"]);
console.log(obj);
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.map((prop) => {
if (typeof prop !== "string") {
throw new Error("Invalid prop");
}
const within = prop in v;
if (!within) {
errorPropsRef.push(prop); // mutate
}
return within;
})
.every((flag) => flag);
}
export function assertMatchedType(
v: unknown,
props: UnionToUnionTuple>,
target = ""
): asserts v is T {
const errorPropsRef: string[] = []; // ࢠʹΛ֨ೲͤ͞ΔͨΊͷۭྻࢀর
if (!isMatchedType(v, props, errorPropsRef, target)) {
// ͜͜ʹ֘͢Δͱ͖ errorPropsRef ྻͷதʹΤϥʔՕॴ͕٧·͍ͬͯΔɻ
throw new Error(
`${target} should be aligned type. ${
0 < errorPropsRef.length ? `[${errorPropsRef.join(", ")}]` : ""
}`.trim()
);
}
}
ศརͳͱ͜Ζ
w ܕఆ͕ٛมΘΔͱɺ
ୈҾͰٻΊΒΕΔ
Ҿͷܕ͕มΘΔ
w ܕఆ͚ٛͩͯ͠ɺ
ϥϯλΠϜଆ͕ͬͯͳ͍ঢ়گΛ͙
type User = {
id: number;
name: string;
email: string;
};
const obj: unknown = { id: 1, name: "foo" };
assertMatchedType(obj, ["id", "name"]);
console.log(obj);
Argument of type '["id", "name"]' is not assignable to
parameter of type 'UnionToUnionTuple<"id" | "name" |
"email">'.
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function assertObject(
v: unknown,
target = ""
): asserts v is Record {
if (!isObject(v)) {
throw new Error(`${target} should be object`.trim());
}
}
function isMatchedType(
v: unknown,
props: UnionToUnionTuple>,
errorPropsRef: string[],
target = ""
): v is T {
assertObject(v, target);
if (new Set(props).size !== props.length) {
throw new Error("Invalid props");
}
return props
.map((prop) => {
if (typeof prop !== "string") {
throw new Error("Invalid prop");
}
const within = prop in v;
if (!within) {
errorPropsRef.push(prop); // mutate
}
return within;
})
.every((flag) => flag);
}
export function assertMatchedType(
v: unknown,
props: UnionToUnionTuple>,
target = ""
): asserts v is T {
const errorPropsRef: string[] = []; // ࢠʹΛ֨ೲͤ͞ΔͨΊͷۭྻࢀর
w ศརؔΛassertObject()Λࣄલʹ
࡞͓ͬͯ͘
w ϓϩύςΟࢦఆͯ͢ϢχʔΫͰ͋Δ͜ͱΛ
อূ
w ͻͱͭͻͱͭinΛͬͯ֬ೝ
w ͳ͚ΕΤϥʔࢀরʹه
ϥϯλΠϜଆͷΈ
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* { a?: string; b: number; c?: any; d: any } Λ
* { b: number; d: any } ͚ͩʹ͢Δɻ
*
* AnyAs0 ͕ͳ͍ͱ ?: any ͷରԠ͕࿙ΕΔͷͰҙɻ
*/
type RemoveOptionalProperties = {
[P in keyof RemoveNeverProperties<
UndefinedAsNever>>>
>]: T[P];
};
function isObject(v: unknown): v is Record {
if (typeof v !== "object") {
return false;
}
return v !== null;
}
function assertObject(
v: unknown,
target = ""
): asserts v is Record {
if (!isObject(v)) {
throw new Error(`${target} should be object`.trim());
}
}
function isMatchedType(
v: unknown,
props: UnionToUnionTuple>,
errorPropsRef: string[],
target = ""
): v is T {
assertObject(v, target);
if (new Set(props).size !== props.length) {
throw new Error("Invalid props");
}
return props
.map((prop) => {
w ศརؔassertObject()
"TTFSUJPOGVODUJPOTͷ
͓खຊͷΑ
͏ͳؔ
assertObject()
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w ͔͜͜Β5ZQF4DSJQUͷຊؾ
w ͯ͢ͷϓϩύςΟ
Λྻڍ͍ͨ͠
w PQUJPOBMͳϓϩύςΟݕূͨ͘͠ͳ͍
w PQUJPOBMͳϓϩύςΟॻ͔ͳ͘
ͯ
ίϯύΠϧΤϥʔʹͨ͘͠ͳ͍
w ͦΕΛ͢ΔͨΊͷܕύζϧ
ܕύζϧ
: false;
type RemoveNeverProperties = Pick<
T,
{
[P in keyof T]: [T[P]] extends [never] ? never : P;
}[keyof T]
>;
type AnyAs0 = {
[P in keyof T]: TypeEq extends true ? 0 : T[P];
};
type UnknownAs0 = {
[P in keyof T]: TypeEq extends true ? 0 : T[P];
};
type OptionalAsUndefined = {
[P in keyof T]: T[P] extends NonNullable ? T[P] : undefined;
};
type UndefinedAsNever = {
[P in keyof T]-?: T[P] extends undefined ? never : T[P];
};
/**
* { a?: string; b: number; c?: any; d: any } Λ
* { b: number; d: any } ͚ͩʹ͢Δɻ
*
* AnyAs0 ͕ͳ͍ͱ ?: any ͷରԠ͕࿙ΕΔͷͰҙɻ
*/
type RemoveOptionalProperties = {
[P in keyof RemoveNeverProperties<
UndefinedAsNever>>>
>]: T[P];
};
function isObject(v: unknown): v is Record {
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: false;
type RemoveNeverProperties = Pick<
T,
{
[P in keyof T]: [T[P]] extends [never] ? never : P;
}[keyof T]
>;
type AnyAs0 = {
[P in keyof T]: TypeEq extends true ? 0 : T[P];
};
type UnknownAs0 = {
[P in keyof T]: TypeEq extends true ? 0 : T[P];
};
type OptionalAsUndefined = {
[P in keyof T]: T[P] extends NonNullable ? T[P] : undefined;
};
type UndefinedAsNever = {
[P in keyof T]-?: T[P] extends undefined ? never : T[P];
};
/**
* { a?: string; b: number; c?: any; d: any } Λ
* { b: number; d: any } ͚ͩʹ͢Δɻ
*
* AnyAs0 ͕ͳ͍ͱ ?: any ͷରԠ͕࿙ΕΔͷͰҙɻ
*/
type RemoveOptionalProperties = {
[P in keyof RemoveNeverProperties<
UndefinedAsNever>>>
>]: T[P];
};
function isObject(v: unknown): v is Record {
Ṗͷຐ๏
w AnyAs0ͱUnknownAs0Ͱɺ
anyܕͱ
unknownܕΛҰ୴ͯ͢
0ܕ
ʢϦςϥϧܕʣ
ʹஔ͖͑Δ
w PQUJPOBMͰ͋Ε
ͯ͢undefinedʹ͢Δ
w 0ܕʹஔ͖͓͔͑ͯͳ͍ͱ
PQUJPOBManyͱPQUJPOBMunknown͕
ਖ਼͘͠ॲཧ͞Εͳ͍
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: false;
type RemoveNeverProperties = Pick<
T,
{
[P in keyof T]: [T[P]] extends [never] ? never : P;
}[keyof T]
>;
type AnyAs0 = {
[P in keyof T]: TypeEq extends true ? 0 : T[P];
};
type UnknownAs0 = {
[P in keyof T]: TypeEq extends true ? 0 : T[P];
};
type OptionalAsUndefined = {
[P in keyof T]: T[P] extends NonNullable ? T[P] : undefined;
};
type UndefinedAsNever = {
[P in keyof T]-?: T[P] extends undefined ? never : T[P];
};
/**
* { a?: string; b: number; c?: any; d: any } Λ
* { b: number; d: any } ͚ͩʹ͢Δɻ
*
* AnyAs0 ͕ͳ͍ͱ ?: any ͷରԠ͕࿙ΕΔͷͰҙɻ
*/
type RemoveOptionalProperties = {
[P in keyof RemoveNeverProperties<
UndefinedAsNever>>>
>]: T[P];
};
function isObject(v: unknown): v is Record {
Ṗͷຐ๏
w undefinedΛͯ͢PQUJPOBMΛ֎ͭͭ͠
neverʹஔ͖͑Δ
w neverͰ͋Εɺ
ͦΕΒΛͯ͢
PickΛͬͯআڈ͢Δ
w ͜ΕundefinedΛؚΊଞͷܕͰ
͜ͷΑ
͏ͳॲཧ͕࣮ݱͰ͖ͣ
neverͷΈআڈͰ͖Δ
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ܕύζϧͷ൪ਓ
w ܕύζϧΛॻ͍͍ͯΔͱ͖ݕূ͕ࠔ
w TypeEqʻA, BʼΛͬͯ
ܕςε
τΛॻ͘
ͱΑ͍
w AnyAs0
UnknownAs0Ͱ༻
> = true extends N ? [] : Push>, L>;
type Tuple = [TItem, ...TItem[]] & {
length: TLength;
};
/**
* Tuple [string, string, string] Λฦ͢
* ͦΕΛԠ༻ͯ͠ 'a' | 'b' Λ ['a' | 'b', 'a' | 'b'] ʹ͢Δ
*
* 'a' | 'b'
* => ['a' | 'b', 'a' | 'b']
* 'a' | 'b' | 'c'
* => ['a' | 'b' | 'c', 'a' | 'b' | 'c', 'a' | 'b' | 'c']
*/
type UnionToUnionTuple = Tuple["length"]>;
type TypeEq = (() => T extends A ? 1 : 2) extends () => T extends B
? 1
: 2
? true
: false;
type RemoveNeverProperties = Pick<
T,
{
[P in keyof T]: [T[P]] extends [never] ? never : P;
}[keyof T]
>;
type AnyAs0 = {
[P in keyof T]: TypeEq extends true ? 0 : T[P];
};
type UnknownAs0 = {
[P in keyof T]: TypeEq extends true ? 0 : T[P];
};
type OptionalAsUndefined = {
https://qiita.com/kgtkr/items/2a8290d1b1314063a524
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type UnionToIntersection = (U extends any ? (k: U) => void : never) extends (
k: infer I
) => void
? I
: never;
type LastOf = UnionToIntersection<
T extends any ? () => T : never
> extends () => infer R
? R
: never;
type Push = [...T, V];
type UnionToTuple<
T,
L = LastOf,
N = [T] extends [never] ? true : false
> = true extends N ? [] : Push>, L>;
type Tuple = [TItem, ...TItem[]] & {
length: TLength;
};
/**
* Tuple [string, string, string] Λฦ͢
* ͦΕΛԠ༻ͯ͠ 'a' | 'b' Λ ['a' | 'b', 'a' | 'b'] ʹ͢Δ
*
* 'a' | 'b'
* => ['a' | 'b', 'a' | 'b']
* 'a' | 'b' | 'c'
* => ['a' | 'b' | 'c', 'a' | 'b' | 'c', 'a' | 'b' | 'c']
*/
type UnionToUnionTuple = Tuple["length"]>;
Ṗͷຐ๏
w PQUJPOBMͳϓϩύςΟ
Λͯ͢
আڈͨ͠ͷͰɺ
ΓͷඞਢϓϩύςΟ
Λ
ྻڍ͠λϓϧͰड͚औΓ͍ͨ
w UnionToTupleΛ͑keyof Tͷ
݁ՌΛλϓϧͱͯ͠ѻ͑Δ
w ͔͠͠ॱෆಉͰ͋Δ
ʢఆ͕ٛهड़ॱʹ
ͳΒͳ͍ʣ
͜ͱͰײతͰͳ͍ͨΊ
UnionToUnionTupleͰهड़ॱΛ
ࣗ༝ʹ͢Δ
w ϥϯλΠϜͰnew Set()Λͨ͠ͷ
͜Εରࡦ
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͜Ε͕࣮ݱͰ͖Δ
w ܕఆ͕ٛมΘΔͱɺ
ୈҾͰٻΊΒΕΔ
Ҿͷܕ͕มΘΔ
w ܕఆ͚ٛͩͯ͠ɺ
ϥϯλΠϜଆ͕ͬͯͳ͍ঢ়گΛ͙
.map((prop) => {
if (typeof prop !== "string") {
throw new Error("Invalid prop");
}
const within = prop in v;
if (!within) {
errorPropsRef.push(prop); // mutate
}
return within;
})
.every((flag) => flag);
}
export function assertMatchedType(
v: unknown,
props: UnionToUnionTuple>,
target = ""
): asserts v is T {
const errorPropsRef: string[] = []; // ࢠʹΛ֨ೲͤ͞ΔͨΊͷۭྻࢀর
if (!isMatchedType(v, props, errorPropsRef, target)) {
// ͜͜ʹ֘͢Δͱ͖ errorPropsRef ྻͷதʹΤϥʔՕॴ͕٧·͍ͬͯΔɻ
throw new Error(
`${target} should be aligned type. ${
0 < errorPropsRef.length ? `[${errorPropsRef.join(", ")}]` : ""
}`.trim()
);
}
}
type User = {
id: number;
name: string;
email: string;
};
const obj: unknown = { id: 1, name: "foo" };
assertMatchedType(obj, ["id", "name"]);
console.log(obj);
Argument of type '["id", "name"]' is not assignable to
parameter of type 'UnionToUnionTuple<"id" | "name" |
"email">'.
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.map((prop) => {
if (typeof prop !== "string") {
throw new Error("Invalid prop");
}
const within = prop in v;
if (!within) {
errorPropsRef.push(prop); // mutate
}
return within;
})
.every((flag) => flag);
}
export function assertMatchedType(
v: unknown,
props: UnionToUnionTuple>,
target = ""
): asserts v is T {
const errorPropsRef: string[] = []; // ࢠʹΛ֨ೲͤ͞ΔͨΊͷۭྻࢀর
if (!isMatchedType(v, props, errorPropsRef, target)) {
// ͜͜ʹ֘͢Δͱ͖ errorPropsRef ྻͷதʹΤϥʔՕॴ͕٧·͍ͬͯΔɻ
throw new Error(
`${target} should be aligned type. ${
0 < errorPropsRef.length ? `[${errorPropsRef.join(", ")}]` : ""
}`.trim()
);
}
}
࿙Εʹ͍ͭͯ
w id͕number
name͕stringͰ͋Δ͜ͱ
·ͰΈͯ͘Εͳ͍
w Α
Γ҆શʹ͍ͨ͠ͳΒͯ͢ͷϓϩύςΟͷܕΛ
unknownܕʹ͢Δͷ͕Α͍
w ͦͷ߹assertString()
assertNumber()ͳͲͷؔͱΈ߹ΘͤΔ
type User = {
id: unknown;
name: unknown;
email: unknown;
};
const obj: unknown = { id: 1, name: "foo" };
assertMatchedType(obj, ["id", "name"]);
console.log(obj);
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$POEJUJPOBM5ZQFTΛۃΊΔͱָ͍͠
w $POEJUJPOBM5ZQFT࣮͔ͳΓͷදݱྗ͕͋Δ
IUUQTXXXUZQFTDSJQUMBOHPSHEPDTIBOECPPLDPOEJUJPOBMUZQFTIUNM
w Ұݟݫͦ͠͏ͳܕਪͰ࣮ॻ͚ͨΓ͢Δ
w $POEJUJPOBM5ZQFTΛۃΊΑ
͏
w asېࢭͰ͖Δ
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5IBOLZPV
https://gist.github.com/okunokentaro/74361c2683bd8e0f349d21ddebe189cf